Centering device



Oct. 18, 1949." Q-VANDERSON 2,484,801

CENTER ING DEVICE Filed July 1, 1944 Patented Oct. 18, 1949 UNITED STATES PATENT OFFICE CENTERING DEVICE Olaf V. Anderson, Providence, R. I.

Application July 1, 1944, Serial No. 543,068

1 Claim. 1

The present invention relates to machine tool apparatus, and has particular reference to centering devices for lathe operations.

The principal object of the invention is to provide a simple and easily operated centering device for quickly determining when the work is accurately centered in the lathe.

Another object of the invention is to provide a centering bar made of a small number of readily manufactured and assembled parts.

With the above and other objects and advantageous features in view, the invention consists of a novel arrangement of parts more fully disclosed in the detailed description following, in conjunction with the accompanying drawings, and more specifically defined in the claim appended thereto.

In the drawings,

Fig. 1 is an elevation of an illustrative centering bar construction embodying the invention;

Fig. 2 is a view similar to Fig. 1, parts being in section and other parts broken away;

Fig. 3 is a perspective view of the tail stock portion of the centering bar before assembly; and

Fig. 4 is a perspective view of the head stock portion of the centering bar before assembly.

It has been found desirable to provide a simple, easily operated device for determining when a piece of work is accurately centered in a lathe. To this end, I have devised an elongated centering bar construction, one end of the bar being adapted to engage the center of the work and the other end of the bar being adapted to seat on the tail stock of the lathe, whereupon a slow rotation of the head chuck immediately indicates whether or not the work is accurately centered in the head stock. If the work is accurately centered the longitudinal axis of the centering bar is aligned with the head and tail centers and there is no off-center rotation of the centering bar; if the work is not centered the head stock end of the centering bar will describe a circle the center of which is the proper work centering location.

Referring to the drawings, the centering bar HJ includes a head stock rod member H, see Fig. 4, which has one end 12 formed as a centering cone, the other end I3 having a longitudinal bore 14 which extends inwardly for a predetermined distance, the wall of the bore being cut away adjacent the end to provide a longitudinual slot opening IS. A cooperating tail stock member 16, see Fig. 3, is preferably formed from solid 2 diameter of the rod member I I and having a centering recess IS in its end, a knurled cylindrical boss 20 being positioned contiguous to the end is and being of slightly greater diameter than the rod member II.

A compression spring 2| is positioned in the bore E4, the end I! of the member 16 is seated in the bore, and a lock pin 22 is passed through the slot 15 to seat in a transverse pin bore 22a in the end I! to securely lock the two members together. A sleeve 23, preferably knurled, and which is of the proper internal diameter to slidably telescope over the rod member H, is then passed over the cone end of the rod member ii and is force-pressed over the knurled boss 29 to effectively seat over the slot opening I5 and prevent dislodging of the pin 22, thus enclosing all the operating parts of the centering bar.

The above described construction provides a simple and eifective centering bar arrangement which can be manufactured at low cost, and which provides a substantial amount of resilient play between the ends of the centerin bar to permit changing the overall length and thus facilitating its use. When work to be machined is mounted in the head stock the centering cone i2 is inserted in the work center, the sleeve is pulled to shorten the length, and the tail stock is moved up to seat in the centering recess It. The work is then slowly turned, preferably by hand, and the resulting rotation of the centering bar immediately discloses whether the work is accurately centered. If the work is not centered, the head stock end of the centering bar describes a circle the radius of which is the distance oif center, whereby the necessary correction is quickly and easily made. If desired, a precision indicator gauge may be used to determine the exact amount of oif-centering. As soon as the work is accurately centered, the centering bar is quickly removed by pulling the sleeve to compress the spring and shorten the length.

While I have described a specific constructional embodiment of my invention, it is obvious that changes in the size, 1e shape, and the arrangement of the parts may be made to meet the requirements for different centering uses and that the invention may be applied to different centering indicator constructions, without departing from the spirit and the scope of the invention as defined in the appended claim.

I claim:

A centering bar construction for a lathe, comprising a rod member having a centering cone at one end and a longitudinal bore in the other end, said bore end having a longitudinal wall slot,

3 4 a second member having a centering recess in REFERENCES CITED one end and having the other end slidably seated The following references are of record m the in said bore, a compression sprin in said bore file of this patent, normally urging the members into overall length extending relation, pin means positioned in said 5 UNITED STATES PATENTS Wall slot and seated in the slidable end of the Number Name Date second member, whereby said members have rela- 685 288 Miller Oct 29 1901 tive movement corresponding to the movement of 1,414:433 S 'IIIII M'ay 1922 the pin means in the wall slot, and a sleeve secured to the second member and slidable over the 10 other member and extending over said wall slot.

OLAF V. ANDERSON. 

